Biomedical subjects

T S Chen

Publications and source records attributed to T S Chen.

At least 73 records · Page 4Linked to original sources

PubMed1996

Measurement of 3 beta-hydroxysteroid delta 7-reductase activity in cultured skin fibroblasts utilizing ergosterol as a substrate: a new method for the diagnosis of the Smith-Lemli-Opitz syndrome.

A new sensitive and specific method for the evaluation of 3 beta-hydroxysteroid delta 7-reductase activity, the defective enzyme in the Smith-Lemli-Opitz (SLO) syndrome, is described. The assay is based on the use of gas chromatography-mass spectrometry with selected-ion monitoring to measure the mass of brassicasterol (ergosta-5,22-dien-3 beta-ol) produced by the incubation of ergosterol (ergosta-5,7,22-trien-3 beta-ol) with cultured human skin fibroblasts. Although the conversion of ergosterol to brassicasterol was slower than the transformation of [3H]7-dehydrocholesterol to [3H] cholesterol, cells from control subjects produced brassicasterol efficiently. In contrast, cells form SLO patients produced very little brassicasterol (P < 0.0001, patients vs. parents or vs. controls). These results indicate that the reduction of ergosterol can be used as an assay for 3 beta-hydroxysteroid delta 7-reductase in human skin fibroblasts, which avoids the many problems caused by the instability and lack of availability of radiolabeled 7-dehydrocholesterol. The present method made it possible to diagnose the SLO syndrome with high sensitivity and reliability using a commercially available compound.

Cholestadienols↗

PubMed1995

A morphometric analysis of bipolar and multipolar TH-IR neurons treated with the neurotoxin MPP+ in co-cultures from mesencephalon and striatum of embryonic C57BL/6 mice.

Mesencephalic cultures contain two morphologically different tyrosine hydroxylase (TH)-immunoreactive (IR) neurons, fusiform bipolar, and pyramidal multipolar, which project to different anatomical structures (ventral striatum and neostriatum). The possibility of functional difference of these cells in Parkinson's disease led us study the effect of 1-methyl-4-phenylpyridinium (MPP+) on them. Survival and morphology of the two groups was studied in dissociated co-cultures from mesencephalon and striatum of embryonic C57BL/6 mice. Cells were grown at first in serum containing medium and then in serum free medium supplemented with hormones. Cultures were exposed to different concentrations of MPP+ on day 9 and 13 for 24 hr. They were fixed and stained with an anti-TH antibody. 0.1-1.0 microM MPP+ caused a dramatic reduction of the total area of TH-IR neurons. At 0.1 microM MPP+ some area was reduced, at 0.5 microM it appeared similar to controls, and decreased further at 1.0 microM. The relation of soma to total area showed that the decrease of the neuronal size was mainly due to the degeneration of the neuronal processes. The length of neuronal tree as well as the number of terminal segments were reduced dose dependently when cells were treated with the toxin. Similar results were obtained for bipolar and multipolar neurons. A significant difference in the decrease in total area was observed between the two age groups when cells were treated with MPP+, as older cells appeared to be more sensitive. When other parameters were checked no apparent difference was present.

1-Methyl-4-phenylpyridinium↗

PubMed1995

MPP+ selectively affects calcium homeostasis in mesencephalic cell cultures from embryonal C57/Bl6 mice.

1-Methyl-4-phenylpyridinium (MPP+), the active metabolite of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) serves as a valuable tool in animal models of Parkinson's disease. Primary cell cultures of mesencephalon from C57/Bl6 mice were used to investigate the effects of various dopaminergic neurotoxins on the intracellular calcium metabolism. MPP+ was compared to its precursor MPTP and a structural analogue paraquat (methylviologen). Direct addition of these neurotoxins (10 microM) to fura-2-labeled cells did not change intracellular calcium concentrations in the presence of 1 mM extracellular calcium. When mesencephalic neurons were exposed to the compounds for 24 hours, only MPP+ led to an increase in calcium concentration in the absence and presence of extracellular calcium (36%, p < 0.05 and 47%, p < 0.01 versus control group). Intracellular calcium concentrations in cortical cultures devoid of dopaminergic cells were not changed by the above neurotoxins. Thus MPP+ is shown to selectively increase intracellular calcium concentrations in mesencephalic cultures.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗

PubMed1995

Microbial transformation of N-heptyl physostigmine, a semisynthetic alkaloid inhibitor of cholinesterase.

The microbiological transformation of N-heptyl physostigmine (L-693,487) (1), a semisynthetic physostigmine cholinesterase inhibitor, was investigated using Verticillium lecanii MF 5713 (ATCC 74148), Acremonium sp MF 5723 (ATCC 74164) and Actinoplanes sp MA 6559 (ATCC 53771). Nine microbial metabolites (2-10) of 1 were isolated and purified using reversed-phase HPLC. The structures of the metabolites were established using spectroscopic techniques including MS and NMR. Some of the microbial metabolites were identical to metabolites present in urine of a dog treated with 1.

Acremonium↗

PubMed1995

Treatment of the cholesterol biosynthetic defect in Smith-Lemli-Opitz syndrome reproduced in rats by BM 15.766.

BACKGROUND & AIMS: The Smith-Lemli-Opitz syndrome is a recessive inherited disorder characterized by neurological developmental defects and dysmorphic features with a defect in cholesterol synthesis at the conversion of 7-dehydrocholesterol to cholesterol. BM 15.766 inhibits 7-dehydrocholesterol-delta 7-reductase and reproduces the biochemical defect. The aim of this study was to investigate the effects of cholesterol, cholic acid, and lovastatin feeding on rats fed BM 15.766. METHODS: Plasma cholesterol and 7-dehydrocholesterol concentrations were related to the hepatic 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase. RESULTS: With the inhibitor treatment, plasma cholesterol concentrations decreased 67%; 7-dehydrocholesterol concentrations increased from trace to 17 mg/dL; and hepatic HMG-CoA reductase activity and messenger RNA levels were stimulated 74% and two times, respectively. In inhibitor-treated rats, feeding cholesterol increased plasma cholesterol concentrations 3.7 times, decreased 7-dehydrocholesterol concentrations 88%, and reduced elevated HMG-CoA reductase activity and messenger RNA levels 74% and 49%. Feeding cholic acid increased plasma cholesterol without reducing 7-dehydrocholesterol concentrations. The combination of cholic acid and cholesterol enhanced plasma cholesterol 9.5 times without decreasing 7-dehydrocholesterol levels. Feeding lovastatin depressed plasma cholesterol further without reducing 7-dehydrocholesterol levels. CONCLUSIONS: Cholesterol is essential to correct abnormal cholesterol synthesis induced by BM 15.766 in rats by expanding the pool and inhibiting HMG-CoA reductase. Neither cholic acid nor lovastatin are effective separately, but cholic acid plus cholesterol may offer some additional benefit.

Acyl Coenzyme A↗

PubMed1995

Gastric inhibitory polypeptide and gastric acid secretion in pregnant rats.

The effects of pregnancy on the basal and pentagastrin-stimulated gastric acid secretion and the level of plasma gastric inhibitory polypeptide (GIP) in rats were studied on pentobarbital-anaesthetized non-pregnant rats and rats in the 1st, 2nd, or 3rd week of gestation. Acid output was determined by titration of the gastric perfusate. Basal secretion was collected for 45 min before a 30 min infusion of pentagastrin (8 micrograms/ml/300 g body weight). Concentration of plasma GIP was measured by a radioimmunoassay (RIA). The immunoreactivity of GIP-like substance in the extract of the rat placenta collected from the rat at day 21 of gestation was examined by RIA. The biological activity of GIP-like substance in the rat placenta extract was tested by the reduction of pentagastrin-stimulated gastric acid secretion in male rats. The basal level of gastric secretion was higher in late pregnancy as compared with the non-pregnant rats. Pentagastrin induced a greater increase of gastric acid secretion in early but not late pregnant rats as compared with the non-pregnant animals. The basal and post-pentagastrin level of plasma GIP was higher in rats in late pregnancy. Both immunoreactivity and biological activity of GIP exist in the rat placenta extract. These results suggest that the normalization of gastric acid secretion in late pregnant rats is at least in part due to the production of GIP-like substance from placenta.

Animals↗

PubMed1995

Effects of sex steroid hormones on gastric emptying and gastrointestinal transit in rats.

In vitro studies have shown that estrogen and progesterone can affect the contractile response and myoelectric activity of the gastrointestinal smooth muscle. The present study was designed to investigate the effect of sex steroid hormones on gastric emptying and gastrointestinal transit were assessed in rats 15 min after intragastric instillation of a test meal containing charcoal and 51Cr. Gastric emptying was determined by measuring the amount of labeled chromium contained in the small intestine as a percentage of the initial amount received. Gastrointestinal transit was evaluated by calculating both the geometric center of distribution of the radiolabeled marker and the charcoal transit in the intestine. The experimental animals included diestrus rats; ovariectomized rats treated with vehicle, estradiol, and/or progesterone; and normal male and orchiectomized rats treated with vehicle or testosterone. Female rats in diestrus had a slower gastric emptying and a lesser geometric center value than ovariectomized rats. Estradiol inhibited gastric emptying but did not affect gastrointestinal transit. Progesterone increased gastric emptying. Progesterone at lower dose (10 mg/kg) decreased the geometric center compared with higher doses (20 or 40 mg/kg) or vehicle controls. A mixture of estradiol (10 micrograms/kg) and progesterone (20 mg/kg) inhibited gastric emptying to a similar degree as estradiol (10 micrograms/kg) did. Testosterone had no influence on gastric emptying or gastrointestinal transit. These results suggest that estradiol and a mixture of estradiol and progesterone inhibit, whereas progesterone enhances, gastric emptying. Testosterone did not play a role in gastrointestinal motility.

Animals↗

PubMed1995

Reproducing abnormal cholesterol biosynthesis as seen in the Smith-Lemli-Opitz syndrome by inhibiting the conversion of 7-dehydrocholesterol to cholesterol in rats.

The Smith-Lemli-Opitz syndrome is a recessive inherited disorder characterized by neurologic developmental defects and dysmorphic features in many organs. Recently, abnormal cholesterol biosynthesis with impaired conversion of 7-dehydrocholesterol to cholesterol has been discovered in homozygotes. To reproduce the biochemical abnormality, BM 15.766, a competitive inhibitor of 7-dehydrocholesterol-delta 7-reductase, the enzyme that catalyzes the conversion of 7-dehydrocholesterol into cholesterol was fed by gavage to rats. After 14 d, plasma cholesterol concentrations declined from 48 mg/dl to 16 mg/dl and 7-dehydro-cholesterol levels rose from trace to 17 mg/dl. Hepatocytes surrounding the central vein developed balloon necrosis. Stimulating cholesterol synthesis with cholestyramine followed by BM 15.766 produced an additional 40% decline (P < 0.05) in plasma cholesterol and 34% increase in 7-dehydrocholesterol levels compared to the inhibitor alone. Adding 2% cholesterol to the diet during the second week of BM 15.766 treatment increased plasma cholesterol threefold and decreased 7-dehydrocholesterol concentrations 55%. Hepatic 3-hydroxy-3-methylglutaryl co-enzyme A (HMG-CoA) reductase activity increased 73% with a 3.9-fold rise in mRNA levels but cholesterol 7 alpha-hydroxylase activity decreased slightly though mRNA levels increased 1.4 times with BM 15.766 treatment. These results demonstrate that BM 15.766 is a potent inhibitor of 7-dehydrocholesterol-delta 7-reductase. The model reproduces abnormal cholesterol biosynthesis as seen in the Smith-Lemli-Opitz syndrome and is useful to test different treatment strategies. Stimulating early steps of cholesterol synthesis worsens the biochemical abnormalities while feeding cholesterol inhibits abnormal synthesis, improves the biochemical abnormalities and prevents liver damage.

Abnormalities, Multiple↗

PubMed1995

Unexpected inhibition of cholesterol 7 alpha-hydroxylase by cholesterol in New Zealand white and Watanabe heritable hyperlipidemic rabbits.

We investigated the effect of cholesterol feeding on plasma cholesterol concentrations, hepatic activities and mRNA levels of HMG-CoA reductase and cholesterol 7 alpha-hydroxylase and hepatic LDL receptor function and mRNA levels in 23 New Zealand White (NZW) and 17 Watanabe heritable hyperlipidemic (WHHL) rabbits. Plasma cholesterol concentrations were 9.9 times greater in WHHL than NZW rabbits and rose significantly in both groups when cholesterol was fed. Baseline liver cholesterol levels were 50% higher but rose only 26% in WHHL as compared with 3.6-fold increase with the cholesterol diet in NZW rabbits. In both rabbit groups, hepatic total HMG-CoA reductase activity was similar and declined > 60% without changing enzyme mRNA levels after cholesterol was fed. In NZW rabbits, cholesterol feeding inhibited LDL receptor function but not mRNA levels. As expected, receptor-mediated LDL binding was reduced in WHHL rabbits. Hepatic cholesterol 7 alpha-hydroxylase activity and mRNA levels were 2.8 and 10.4 times greater in NZW than WHHL rabbits. Unexpectedly, cholesterol 7 alpha-hydroxylase activity was reduced 53% and mRNA levels were reduced 79% in NZW rabbits with 2% cholesterol feeding. These results demonstrate that WHHL as compared with NZW rabbits have markedly elevated plasma and higher liver cholesterol concentrations, less hepatic LDL receptor function, and very low hepatic cholesterol 7 alpha-hydroxylase activity and mRNA levels. Feeding cholesterol to NZW rabbits increased plasma and hepatic concentrations greatly, inhibited LDL receptor-mediated binding, and unexpectedly suppressed cholesterol 7 alpha-hydroxylase activity and mRNA to minimum levels similar to WHHL rabbits. Dietary cholesterol accumulates in the plasma of NZW rabbits, and WHHL rabbits are hypercholesterolemic because reduced LDL receptor function is combined with decreased catabolism of cholesterol to bile acids.

Alanine Transaminase↗

PubMed1995

Relationship of biopsy and final specimens in evaluation of tumor thickness in floor of mouth carcinoma.

A number of studies have suggested that tumor thickness may be a valuable prognostic indicator in the evaluation of head and neck cancers. This study examined the relationship between tumor thickness measured in preliminary biopsy specimens with the final specimens obtained in 31 patients with floor of mouth epidermoid carcinoma. There was a significant statistical correlation between biopsy and final specimens. The Pearson's product-moment correlation coefficient was 0.58, which corresponded to a significance level of P < .0005. The results of this study showed that those patients who had biopsies with a thickness less than or equal to 1 mm were likely to have final specimens with a thickness less than 2 mm. All patients with a thickness greater than 2 mm had a final specimen with a thickness greater than 3.5 mm. Modification of current biopsy techniques may result in values more predictive of final thickness measurements.

Biopsy↗

PubMed1995

Defective conversion of 7-dehydrocholesterol to cholesterol in cultured skin fibroblasts from Smith-Lemli-Opitz syndrome homozygotes.

The Smith-Lemli-Opitz syndrome is a common birth defect syndrome characterized biochemically by low plasma cholesterol levels and high concentrations of the cholesterol precursor 7-dehydrocholesterol. The present study was undertaken to prove that the enzyme defect is at the step in which 7-dehydrocholesterol is converted into cholesterol and to establish a new biochemical method for the diagnosis of this disease. We assayed the latter part of the cholesterol biosynthetic pathway by incubating [3H]lathosterol (the immediate precursor of 7-dehydrocholesterol) with cultured skin fibroblasts from 15 homozygous patients, 14 obligate heterozygous parents, and 8 controls, and measuring its conversion to 7-dehydrocholesterol and cholesterol. The formation of cholesterol from lathosterol in parents was not significantly different from that in controls. In contrast, cells from patients made very little cholesterol (P < 0.0001, patients vs. parents or vs. controls) but readily converted lathosterol to 7-dehydrocholesterol. The defect was especially profound in a subgroup of 8 of the most severely clinically affected patients, as virtually no label was detected in the cholesterol fraction. These results provide compelling evidence that 1) this disease is caused by a primary defect in 7-dehydrocholesterol delta 7-reductase, an essential enzyme in the biosynthesis of cholesterol; 2) the most clinically severe form of the syndrome may be associated with the most inhibited enzyme; and 3) the enzyme lathosterol 5-desaturase that converts lathosterol to 7-dehydrocholesterol is fully intact. The present method using fibroblast and amniocyte cultures establishes it as a useful procedure for the biochemical diagnosis of this syndrome.

Adolescent↗

PubMed1995

A biopsy urease test in the detection of Helicobacter pylori: comparison of antral and body specimens.

BACKGROUND: This study was to compare the difference of positive rate and reaction time between the antrum and the body specimens in duodenal ulcer (n = 124) and non-duodenal ulcer (n = 181) patients. METHODS: A total of 305 subjects with positive urease test were evaluated. During endoscopy each biopsy specimen from the greater curvature side of the antrum and the body was immediately incubated in a thermostatically controlled 37 degrees C waterbath and examined regularly in the first 6 h, and if there was no response, reexamined after 24 hours. A change from orange to pinkish red was considered positive. RESULTS: There was no difference in the positive rate of urease test between the antrum and the body in patients with duodenal ulcer (95.2% vs. 94.4%); whereas, the positive rate was higher in the body specimens than in the antral specimens in patients without duodenal ulcer (p < 0.05, 97.8% vs. 89%). Antral specimens had more rapid color change of urease test than the body specimens patients with duodenal ulcer; whereas no such difference was found in patients without duodenal ulcer. In the antral specimens of patients without duodenal ulcer who were less than 60 years old, the color change was more rapid than in those older than 60 (median 1.0 hr vs. 1.5 hr, p < 0.05). CONCLUSIONS: For better detection of H. pylori colonization using a urease test, it is critical to choose a suitable biopsy site. In non-duodenal ulcer disease, biopsy of the greater curve of the body has a higher detection rate than that of the antrum. In duodenal ulcer disease, biopsy of the antrum is better than that of the body for its quicker reaction.

Adolescent↗

PubMed1995

[Current clinical approaches and gene mutation study of beta-thalassemia major].

Forty-one cases of beta-thalassemia major were assessed for their clinical manifestations and gene mutation. The age distribution was from 1 to 18 years old. Patient's initial clinical symptoms began mostly before 2 years of age (90.2%). Patient's initial hematological data included mean hemoglobin value, 5.8 +/- 1.2 gm/dl, hemoglobin F value, 85.0 +/- 12.1%, hemoglobin A2 value 2.3 +/- 1.8%, reticulocyte count 9.2 +/- 9.0%. Eight different point mutations were characterized. Of these mutations, C to T substitution at nucleotide (nt) 654 of intervening sequence (IVS) 2, accounting for 46.3% of mutant beta-globin genes, is the most common mutation in our series, followed by frameshift codons 41/42 with a four nucleotides (TCTT) deletion for 31.7%; A to G substitution at position -28 of the promotor area for 8.5%; A to T substitution at codon 17 for 6.1%; frameshift codons 27/28 (insertion of C) for 2.4%; G to T substitution at nucleotide 1 of IVS-1 for 2.4%; frameshift codons 71/72 (insertion of A) and IVS-1 3' end TAG-->GAG for 1.2%. The first four mutations account for 92.6% of all beta-globin gene mutations in our series. As to mutations in each individual, the incidence of compound heterozygotes of two different mutations is much higher than homozygotes of a single mutation, 78.0% vs. 22.0%. Compound heterozygotes of C to T substitution at nt 654 of IVS-2 and frameshift codons 41/42 with a four nucleotides deletion is the most common pattern of beta-thalassemia mutation in our patients (41.5%). Patients with beta(0)/-28 beta(+) compound heterozygote mutation had much delayed initial symptoms than beta (0)/beta(0) homozygote mutation, but clinical manifestation may be aggravated when the mutation combined with glucose-6-phosphate dehydrogenase deficiency. Severity of iron overload was significantly correlated with total transfusion amount and patient's age in simple regression analysis (p < 0.001). Splenectomy may effectively prolong transfusion interval, maintain higher hemoglobin level before each transfusion and palliate clinical symptoms (p < 0.01). Iron-chelating agent therapy can effectively lower the total amount of serum ferritin. Higher severity of iron overload correlates with higher incidence of EKG and cardiac abnormalities in patients with beta-thalassemia major.

Adolescent↗

PubMed1995

Integrating a health IC card system into a hospital information system.

As an experiment, a health IC card has been linked into the hospital information system of the National Cheng Kung University (NCKU) Hospital. The NCKU Hospital Information System (NCKU-HIS) services all the procedures for patient registration, billing, prescriptions, and the processing and storing of test results. The health IC card system provides good quality information to the doctors, the hospital, the patients, and the insurance organizations. For a fully comprehensive system, it is essential to integrate the health IC card system into the operational NCKU-HIS, the communication protocols, and the national insurance procedures. The experiment was designed to see if the development of such a system was feasible, and the results have been impressive. It has proved possible to operate the health IC card system, linking into different machines under different computing environments. A single computer system to store all the data of all the patients and to process all the nation's healthcare information would require almost unlimited mainframe processing power and unlimited storage. It would be very difficult to construct such a large computerized information system. All the hospitals would be required to use the same data format to process their information, and a large national healthcare network would have to be built, making the collection and storage of personal medical information very difficult and probably inefficient and unsatisfactory. Even if it was possible, it would be a very costly and time-consuming task. An IC card is cheap and easy to use, and offers an alternative solution to the problem of handling the nation's healthcare information. The original healthcare IC card experiment (started in 1990) was limited to the NCKU Hospital and the Taiwan Government Employees' Clinic. The experimental system was designed to be fully integrated into the NCKU-HIS and has been widely accepted by the users, especially the IC card-holding patients. It is also well-suited to the management of healthcare insurance. An expanded healthcare IC card system was implemented from the end of 1993 and covers six clinics and six hospitals in Penghu County. The operation of the registration and billing subsystems are supported by PC workstations in a client/server network as these subsystems are used very frequently. Some of the other computerized functions in the NCKU-HIS are supported by the mainframe TANDEM computer system. The interfaces with the communication protocols and application software provide for the effective two-way transfer of data and programs. For future use, consideration is being given to the employment of the Health Level Seven (HL/7) protocol for electronic data interchange. National standards such as Chinese information processing, the use of standard codes, the authorization of the content of the IC card, and communication protocols are already incorporated in the system.

Hospital Information Systems↗

PubMed1995

The design and development of a fully integrated hospital information system.

This paper provides an overview of the design and development of a comprehensive integrated hospital information system for the National Cheng Kung University Hospital. This system was designed for a new hospital, to be built on a 'green field' site, and was developed and installed as an integral component of the building of the hospital and the installation of the medical and administrative facilities. The approach necessitated: 1) the specification of requirements with no users to explain what they needed; 2) a study of capacity without the availability of existing data to predict the workload; 3) a performance study in advance of operation to understand system behavior; and 4) the effective scheduling of implementation to ensure congruence with the building and commissioning of the hospital.

Computer Simulation↗

PubMed1994

Selegiline enhances survival and neurite outgrowth of MPP(+)-treated dopaminergic neurons.

Selegiline was added to co-cultures of mesencephalon and neostriatum of C57BL/6 mouse embryos according to three schemes: (i) before and (ii) after cells were exposed to the toxin 1-methyl-4-phenylpyridinium (MPP+), (iii) in control cultures. In all schemes, selegiline enhanced the morphological differentiation of dopaminergic neurons and with delayed treatment, significantly increased their survival. These results indicate that selegiline exhibits trophic-like actions and can rescue MPP(+)-injured dopaminergic neurons in cultures.

1-Methyl-4-phenylpyridinium↗

PubMed1994

Defective cholesterol biosynthesis associated with the Smith-Lemli-Opitz syndrome.

BACKGROUND: The Smith-Lemli-Opitz syndrome (frequency, 1:20,000 to 1:40,000) is defined by a constellation of severe birth defects affecting most organ systems. Abnormalities frequently include profound mental retardation, severe failure to thrive, and a high infant-mortality rate. The syndrome has heretofore been diagnosed only from its clinical presentation. METHODS: Using capillary-column gas chromatography-mass spectrometry, we measured the sterol composition of plasma, erythrocytes, lens, cultured fibroblasts, and feces from five children with the syndrome (three girls and two boys). RESULTS: Plasma cholesterol levels were abnormally low (8 to 101 mg per deciliter [0.20 to 2.60 mmol per liter]) in every patient, being well below the 5th percentile for age- and sex-matched controls. Concentrations of the cholesterol precursor 7-dehydrocholesterol (cholesta-5,7-dien-3 beta-ol), which was not detectable in most of our controls, were elevated (11 to 31 mg per deciliter) more than 2000-fold above normal and were similar to the levels of cholesterol in all tissues from all patients. An isomeric dehydrocholesterol with a structure similar to that of 7-dehydrocholesterol was also detected. CONCLUSIONS: The combination of abnormally low plasma cholesterol levels and a high concentration of the cholesterol precursor 7-dehydrocholesterol points to a major block in cholesterol biosynthesis at the step in which the C-7(8) double bond of 7-dehydrocholesterol is reduced, forming cholesterol. The block may be sufficient to deprive an embryo or fetus of cholesterol and prevent normal development, whereas the incorporation of 7-dehydrocholesterol into all membranes may interfere with proper membrane function.

Abnormalities, Multiple↗

PubMed1994

Microbial transformation of immunosuppressive compounds. III. Glucosylation of immunomycin (FR 900520) and FK 506 by Bacillus subtilis ATCC 55060.

The regiospecific glucosylation of FK 506 and immunomycin (FR 900520) at the 24-hydroxy position was performed using resting cells of Bacillus subtilis ATCC 55060. 24-Glucopyranosyl FK 506 and 24-glucopyranosyl immunomycin were isolated by methylene chloride extraction and purification using reverse phase HPLC. The metabolite structures were established using spectroscopic techniques including MS and NMR. The glucose conjugate was further confirmed by chemical degradation. Enzymatic glucosylation was demonstrated using cell-free extracts derived from Bacillus subtilis ATCC 55060. The 24-glucosyltransferase, which appears UDP-glucose dependent, was solubilized from cell membranes by treatment with 0.1% Nonidet P-40 detergent. The optimal conditions for assay of the enzyme have been determined.

Bacillus subtilis↗